It’s difficult to overstate the local impact of the lurid tale of Jens Soering and Elizabeth Haysom, University of Virginia students who were convicted in the bloodbath murders of her parents more than 30 years ago.

Featured in the trial were blood samples that were said to point toward Mr. Soering’s presence at the scene.

Elizabeth Haysom pleaded guilty to being an accessory before the fact, while Jens Soering, son of a German diplomat, initially pleaded guilty to committing the murders. He later recanted, saying he had pled guilty to protect Elizabeth from Virginia’s electric chair under the mistaken impression he had diplomatic immunity.

Ms. Haysom testified against him at trial and continues to say he is guilty, while he claims she is lying in order to position herself for possible parole.

At the time, the physical evidence seemed convincing. Type O blood was found at the scene; Mr. Soering has Type O blood, while none of the Haysoms did.

But because of doubt over forensic decisions in a number of cases, then-Gov. Mark Warner ordered a systematic review of blood evidence, and — surprise! — DNA evidence turned up in the Soering case.

The forensic investigator at the time had said that no DNA evidence could be drawn from the blood samples. It may be that he simply did not know that better samples were available, says today’s program manager at the Department of Forensic Science.

But two additional samples were discovered and tested in 2009. That test eliminated Mr. Soering as a contributor of those particular samples. It also suggested that two other men might have been at the scene.

Those who believe in Mr. Soering’s innocence include his attorney, Steven Rosenfield, of Charlottesville, and Albemarle County Sheriff Chip Harding.

However, another expert — Betty Layne DesPortes, president-elect of the American Academy of Forensic Sciences — questions the accuracy of the new tests, since the DNA profile was “developed” from eight different samples, six of which included Type A blood, she said.

Meanwhile, additional gruesome details have emerged. Ms. Haysom later said that her mother had sexually abused her for eight years, and that Mr. Soering’s anger over the abuse was a motivator in the murder. But when the sexual abuse issue had been raised during trial, Ms. Haysom denied that any such thing had occurred.

At present, then, we have blood evidence tested by state forensic investigators that does not match Mr. Soering’s DNA, while at least one critic questions that result. And we have a co-conspirator pointing the finger at Mr. Soering, while he questions her honesty.

Neither Mr. Soering nor Ms. Haysom was sentenced to death, so this is not a question of saving someone from capital punishment.

However, the issue of “reasonable doubt” remains important. Is the botching of the initial bloodwork serious enough to cast reasonable doubt of Mr. Soering’s guilt, counteracting Ms. Haysom’s accusation?

Additionally, the fact that these particular samples have been ruled not to be his doesn’t prove that he was not at the scene.

The murderer simply might have not left his own blood behind. Or, in what’s described as a “slaughterhouse” scene, police could have missed collecting the one sample that clearly would have identified the killer.

Since recanting his initial confession, Mr. Soering has maintained his innocence and has repeatedly asked for clemency from a succession of governors. Gov. Terry McAuliffe’s office has indicated he may not have time before he leaves office to review Mr. Soering’s supplemental request with the new DNA evidence.

That punts the issue to incoming Gov. Ralph Northam — a physician who ought to know something about blood samples.

Still, in this confusing case, Mr. Northam is not likely to face an easy decision.